The invention generally relates to the field of laser line illuminators, and specifically relates to systems and methods for measuring the quality of an illumination field from a laser line illumination system.
Laser line illumination systems generally employ an array of light sources, such as light emitting diodes, coupled with optics that produce a laser illumination field in the shape of a line. The optics may include a variety of optical elements including, for example, lenses, micro-lenses, and mirrors, as well as fiber optic cables.
Such systems may be used for a numerous applications, such as in imaging systems in which the laser line illumination field is directed toward a light modulator that modulates the illumination field by either selectively reflecting or transmitting specificed portions of the illumination field. The modulated illumination field is then directed toward an imaging surface in which a portion of imageable media is selectively imaged. Either the illumination field or the imageable surface (such as a drum) is then moved with respect to other so that further portions of the imageable media may then be successively imaged.
Non-uniformities in the illumination field of a laser line illumination system may result in significant imaging inconsistencies that may be difficult to detect or correct. It is desirable that such laser line illumination systems produce an illumination field that has a uniform width throughout the length of the illumination line. It is also desirable that such systems produce an illumination field that has a uniform peak power throughout the illumination line. It is further desirable that such systems produce an illumination field that has a uniform power distribution throughout the length of the illumination line. It is further desirable that such systems produce an illumination field that has a uniform spot size throughout the length of the illumination line.
There is a need therefore, for a system and method of measuring the output characteristics of a laser line illumination system.
The invention provides a system for analyzing an illumination field of a line of laser illumination. The system includes a first movable unit, a second movable unit, and a sensor unit. The first movable unit includes a first opening through which at least a portion of the illumination field may pass. The first movable unit is adapted for movement in a first direction. The sensor unit is adapted to receive illumination and to produce a sensor output signal representative a characteristic of the illumination field. The second movable unit includes a second opening through which at least a portion of the illumination field may pass. The second movable unit is positioned between the first movable unit and the sensor unit and is adapted for movement between at least a first position in which very little or no light from the illumination field may reach the sensor unit, and a second position in which a relatively high amount of light from the illumination field may reach the sensor unit.